Hf alkylation system utilizing alkylate stream reboil

ABSTRACT

A side draw stream from an isostripper to a debutanizer is removed from the isostripper as a liquid stream of normal butane and higher hydrocarbons. The alkylate-containing bottoms fromthe isostripper are used to indirectly heat or reboil the bottom of the debutanizer. Alkylate is recovered from the reboiler line as well as from the debutanizer.

United States Patent [191 m 3,857,904" Y Chapman I Dec. 31, 1974 [54] HF ALKYLATION SYSTEM UTILIZING 2,511,758 6/1950 Weinrich 260/683.48 ALKYLATE STREAM REBOIL 1 3,004,088 10/1961 Hutto 260/683.48

[75] Inventor: Charles C. Chapman, Bartlesville,

Okla. Primary ExaminerDelbert E. Gantz A E. -G.J.,C k' [73] Assrgnee: Phillips Petroleum Company, msmm' mmmer rascma ls Bartlesville, Okla.

[22] Filed: May 7, 1973 211 App]. 1510.; 357,615 [57] ABSTRACT A side draw stream from an isos tripper to a debuta- 52 us. Cl. 260/683.48,J2 60/683.42 him is removed from the o pp a a liquid 51 int. Cl. coves/54 stream of normal butane a d higher hydrocarbons- 58 Field of Search..... 260/683.48, 683.43, 683.58, Th: all fl qq n ei n q t m it e pe 260/633 59 are used to indirectly heator reboil the bottom of the debutanizer. Alkylate is recovered from the reboiler [56 Referen Cit d line as well as from the debutanizer.

UNITED STATES PATENTS 2 Claims, 1. Drawing Figure 2,371.402 3/1945 Mateeretal. "260768343 62 v 42 PROPANE P MP ALKYLATE F L USH In HF alkylation, it is desirable to fractionate a product resulting from reaction of isobutane, olefins, and hydrofluoric acid catalysts while maintaining the energy requirements for said fractionation at a low level. This is particularly important where energy is valuable and the products for generating the energy are in relatively short supply.

This invention, therefore,- resides in an improved HF alkylation system wherein a side draw stream passing from a first fractionation zone into a second fractionation zone is removed from the first fractionation zone at a location at which said side draw stream comprises substantially liquid normal butane and heavier hydrocarbons.

Other aspects, objects, and advantages of the present invention will become apparent from a study of the disclosure, the appended claims, and the drawing.

The drawing is a diagrammatic vie-w of'an example HF alkylation system.

Referring to the drawing, isobutane 2, olefin 3, recycle isobutane 6, liquid feed streams are charged along with liquid hydrofluoric acid catalyst 8 to HF alkylation riser-reaction zone 10, wherein-the isobutane is alkylated with the olefins to produce gasoline alkylate. The emulsion of hydrocarbon and HF catalyst from riserrecovered vapors from an HF stripper 30, are passed to accumulator 31 and an HF phase 32 is recovered,'as

bon phase yield 33 is passed to the HF stripper to yield an LPG (liquefied petroleum gas) propane prod-' uct 29.

A liquid side draw 34, comprising isobutane, is removed from the depropanizer 26 and a portion 36 thereof is vaporized and used to strip the HO rerun unit (not shown). The remainder 38 is further cooled, a portion 38' being used as pump flush and as reflux for the HF rerun unit (not shown), and this remainder 38" is recycled to the alkylation zone as a portion of the recycled isobutane 6..Bottoms 40 from the depropanizer 26, in part are used as other pump flush 42, and the remaindermajor portion 44 is charged to a first fractionation zone or isostripper 48 as the lower" feed thereto. The remainder 46 of the alkylation reactor efreactor 10 is passed to a phase separation zone 14 up of light hydrocarbons, e.g., propane is passed via side draw and bottoms indirect heat exchange 22, 24 to a depropanizer 26. Overhead vapors 28 from the decovered pump flush 49, are'returned via 51 as recycle isobutane liquid 6.

A side draw liquid stream 52 is removed from. for example, above on inter-heater 54 of the isostripper 48 and charged to a second fractionation zone or debuta nizer 5 6. Bottoms from the isostripper 48 are used to indirectly (reboil) heat the bottom of the debutanizer 56, and are removed from the system with the bottoms yield 62 from the debutanizer 56 as the alkylate product.

The side draw stream 52 is withdrawn from the isosv propanizer 26 are condensed, along with subsequently 40 as follows:

EXAMPLE {mums PER my maocmtsm F101} Total Feeg Feed Isohutane Ethane It 6 l0 l0 Propylene 399 99 Propane 27 338 1,9 6 2,310 2,1190

Isobutane 2,603 986 32,951+ 3 ,5 6 33,

Butenes l 127 l 7 Normal Butane 11.0 7h3 3,4 9 h, 262 4,318

mylenes 785' 7 5 Pentanes Plus 772 5 3 ,355 :5 5

Total Hydrocarbon 2,71 0 5, 5 4 3 3 9 47, 9 1 33- 7 Total 2.71m 5,651+ 39,064 amus 10,211

Conduit. Number i (L) (3) 5 (7) 5) (To Recycle 1C 10,077) (To HF Rerun &Pump Flush 833) Pum Flush 288 Benin Stripping 6L Rerun Reflux 91 See drawing for numbers, pressures, temperature:

From DC Side v Side Draw to Bottoms Aceum. To HF Effluent Flush Total Draw Recycle Yield HF Stripper 134,10 7 13,518 M55 ,733 m ss 12 18,773 11,1, 18,917 1o,91o* 10,077 7,A 15 022 Operating Conditions:

Preferred alkylation temperature range 40 F.-l50 F., more preferably 75 F.l40 F. in reaction zone 10.

Preferred HF catalyst to hydrocarbon volume ratio range in reaction zone 1:1 to 10:1. 7

Preferred external isobutane to olefin mol ratio range 2:1 to 3011.

Preferred pressure is sufficient to maintain liquid phases in the alkylation zone, e.g., 150 psia and above.

Preferred isoparaffin feed...isobutane and/or isopentane.

Preferred olefin feed.,.propylene and/or butylenes and/or amyle'nes.

HF catalyst can preferably contain up to about 10 weight percent acid-soluble oils, preferably below weight percent acid-soluble oils, up to weight percent water, preferably less than about 5 weight percent water.

Preferred residence or contact time in the reaction zone is 5 to 500 seconds, more preferably 10 to 240 seconds.

' Typical Tower Conditions Depropanizer 26:

Top Temperature, F. [31

w (continued) 4 Feed to ostripmrv Isostrippe; Yields 5 Lower T61 1 DeC Propane from Over- Pump '10 Side Over- Alkylate BL QEB MA 2 EQELL 5 121 1 392x2 2 221% E2! HEEL @1123 (HF) (167) (167) (167) (167) i Ethane L 6 6 6 I 6 Propylene Propane 500 1,191 6 1, 00 1,500 i 6 1,506 156611166 8 20,238 3,899 21,137 21,096 125 21,221 3 38 3e 3 Butenes' i Normal Butane 2,608 827 3,135 2,582 12 2,591 121 732' 710 22 113 Amylenes I Pentanes P165 3,958 2,160 6,118 192 1 [193 5,331 595 17 57 5,909

Total Hydrocarbon 512 28,301 7,192 35,196 28,676 111 28,820 5,155 1,365 765 a 600 6,055 Total I 51 28,171 .111 28,987 5,155 1,365 765 600 6,0

' fractionation zone, normal butane of a higher purity is passed to the debutanizing zone, 'therebydecreasing the amount of isostripper energy requirements for heating and permitting the use of a smaller debutanizing column,

Other modifications and alterations of this invention will become apparent to those skilled in the art from the foregoing discussion and accompanying drawing, and it should be understood that this invention is not to be unduly limitedthereto.

.What is claimed is:

1. In an HF-alkylation process wherein 'isoparaffin, olefin and hydrofluoric acid catalysts are reacted in a reaction zone to form an alkylate, wherein the alkylatecontaining hydrocarbon is passed into a first fractionation zone to remove u'nreacted isoparaffin, wherein a side draw stream is separated from said first fractionation zone and wherein'said side draw stream is passed into a second fractionation zone,

the improvement which comprises separating said side draw stream from the first fractionation zone as a liquid stream consisting substantially of normal butane and heavier hydrocarbort, separating normal butane from said second fractionation zone, and passing the alkylate-containing bottoms from said first fractionation zone into the bottom portion of said second fractionation zone as reboil for said second fractionation zone.

2. The process of claim 1 wherein a first portion of the alkylate product is recovered from said second fractionation zone and a second portion of said product is recovered from said alkylate-containing bottoms from said first fractionation zone. 

1. IN AN HF-ALKYLATION PROCESS WHEREIN ISOPARAFFIN, OLEFIN AND HYDROFLUORIC ACID CATALYSTS ARE REACTED IN A REACTION ZONE TO FORM AN ALKYLATE, WHEREIN THE ALKYLATE CONTAINING HYDROCRBON IS PASSED INTO A FIRST FRACTIONIZATION ZONE TO REMOVE UNREACTED ISPARAFFIN WHEREIN A SIDE DRAW STREAM IS SEPARATED FROM SAID FIRST FRACTIONIZATION ZONE AND WHEREIN SAID SIDE DRAW STREAM IS PASSED INTO A SECOND FRACTIONIZATION ZONE, THE IMPROVEMENT WHICH COMPRISES SEPARATING SAID SIDE DRAW STREAM FROM THE FIRST FRACTIONATION ZONE AS A LIQUID STREAM CONSISTING SUBSTANTIALLY OF NORMAL BUTANE AND HEAVIER HYDROCARBON, SEPARATING NORMAL BUTANE FROM SAID SECOND FRACTIONATION ZONE, AND PASSING THE ALKYLATE-CONTAINING BOTTOMS FROM SAID FIRST FRACTIONATION ZONE INTO THE BOTTOM PORTION OF SAID SECOND FRACTIONIZATION ZONE AS A REBOIL FOR SAID SECOND FRACTIONATION ZONE.
 2. The process of claim 1 wherein a first portion of the alkylate product is recovered from said second fractionation zone and a second portion of said product is recovered From said alkylate-containing bottoms from said first fractionation zone. 